Question

How Many People Wash Their Hands After Using the Washroom? In Example 1.10 on page \(16,\) we introduce a study by researchers from Harris Interactive who were interested in determining what percent of people wash their hands after using the washroom. They collected data by standing in public restrooms and pretending to comb their hair or put on make-up as they observed patrons' behavior. \({ }^{27}\) Public restrooms were observed at Turner's Field in Atlanta, Penn Station and Grand Central Station in New York, the Museum of Science and Industry and the Shedd Aquarium in Chicago, and the Ferry Terminal Farmers Market in San Francisco. Of the over 6000 people whose behavior was observed, \(85 \%\) washed their hands. Women were more likely to wash their hands: \(93 \%\) of women washed, while only \(77 \%\) of men did. The Museum of Science and Industry in Chicago had the highest hand-washing rate, while men at Turner's Field in Atlanta had the lowest. (a) What are the cases? What are the variables? Classify each variable as quantitative or categorical. (b) In a separate telephone survey of more than 1000 adults, more than \(96 \%\) said they always wash their hands after using a public restroom. Why do you think there is such a discrepancy in the percent from the telephone survey compared to the percent observed?

Short answer

The cases are the over 6000 people observed in various public restrooms, and the variables are the locations of the public restrooms, the number of people who wash their hands, the gender of people, and the percent of people who wash their hands. Discrepancy in results may be attributed to social desirability bias; people claimed they wash their hands over the phone, though the direct observation might show different situation.

Step-by-step solution

Identify and Classify the Cases and Variables

The cases in this study are the over 6000 people whose behavior was observed in the public restrooms. The variables are the locations of public restrooms, the number of people who wash their hands, gender of the people (men and women), and the percent of people who wash their hands. The location of public restrooms and gender are categorical variables, while the number and percent of people who wash their hands are quantitative variables.

Discuss the Discrepancy

The discrepancy in the percent from the telephone survey compared to the observed percent may be due to social desirability bias. This means that people may not always tell the truth and may say what they think the interviewer wants to hear on a phone survey. In the direct observation in public restrooms, however, the true behavior of people is observed, which is likely to be different from what they claim on phone surveys.

Key concepts

Quantitative Variables

Quantitative variables represent information that can be measured and expressed numerically, making them crucial in any statistical analysis. In the context of hand-washing behavior, quantitative variables are the number and percent of people observed washing their hands. These variables offer insight into the magnitude and frequency of hand-washing in different settings and allow for straightforward comparisons and statistical computations. For instance, by acknowledging that 85% of people were observed washing their hands, we can numerically analyze and understand hand-washing habits across different populations or locations, aiding in public health assessments and planning.

Quantitative data is versatile as it can appear in different forms, such as discrete or continuous. Discrete data could be the actual count of people washing hands, while continuous data might pertain to the duration of hand-washing if it were to be measured. It is essential to accurately collect and classify this kind of information to ensure precise conclusions and informed decision-making.

Categorical Variables

Categorical variables classify individuals or items into different groups, which are based on a shared quality or characteristic. Unlike quantitative variables, they cannot be quantified but are vital in revealing patterns or frequencies within subgroups. In our study, the locations of public restrooms and the gender of individuals are categorized as categorical variables. For example, separating data by gender reveals that 93% of women and only 77% of men wash their hands, indicating a significant difference in hand-washing behavior between the sexes. Understanding gender differences is valuable in designing targeted public health campaigns or educational programs.

Such variables can be further defined as nominal, where there is no natural order between categories, such as restroom locations, or ordinal, where the categories have a logical order, although this specific study does not present an example of ordinal data. Categorical variables help us identify and categorize behaviors, which is the first step towards analyzing and understanding the patterns present in the data.

Social Desirability Bias

Social desirability bias is a type of response bias that affects the accuracy of data collected from surveys or questionnaires. It occurs when participants provide answers that they believe are more socially acceptable or favorable rather than being truthful. This bias can lead to discrepancies, as seen in the hand-washing study where a telephone survey reported a higher hand-washing rate (96%) compared to the direct observation (85%). People might overreport positive behaviors, like hand-washing, especially when they believe it is expected of them.

Recognizing the presence of social desirability bias is crucial for researchers as it can skew the results of a study. Therefore, methods that minimize interaction with participants, such as anonymous surveys or, as in this case, discreet observations, are employed to reduce this bias and gather more accurate data on actual behaviors.

Data Collection Methods

Data collection methods are pivotal for acquiring information to be used in research studies. The choice of method affects the accuracy and reliability of the collected data. In the Harris Interactive study of hand-washing behavior, researchers used direct observation, a non-reactive technique, to minimize the impact on the subjects' behavior and reduce biases such as the aforementioned social desirability bias. By pretending to comb hair or apply makeup, observers could blend into the environment and record genuine behaviors.

Comparatively, the telephone survey used a reactive technique where participants were aware they were being questioned and their responses could be influenced by social pressures. Other methods of data collection may include online surveys, face-to-face interviews, focus groups, and experiments, each with its own set of advantages and limitations. The effectiveness of data collection can be improved by using a combination of methods, validating with multiple data sources, or employing measures to increase anonymity and reduce the potential for bias.